It's on to Part III. I will try to keep this brief from here on out because
I dont want this to get tedious. If anything you need me to get in detail about
just post up and we can discuss.
Free Throws
We know from the work of others that every free throw uses about .44
possessions. NBA teams this season averaged about 25 free throw attempts this
season. If we multiple 25 by .44 we get about 11 possessions used on the free
throws. We can use .5 (2 attempts = 1 possession) without much change but we'll
stick with .44 as to account for three point plays and technicals.
Allen Iverson averaged 11.16 attempts per 48 minutes this season. If we multiply
11.16 by .44 we get 4.91 possesions used. These 4.91 possessions are worth about
4.91 points. Iverson made 9.03 free throws. Subtracting the average 4.91 from
9.03 gives 5.12 points above average for Iverson. The formula is than value =
ftm - fta*.44. We also account for missed free throws similarly to missed shots
except of course that not all missed free throws can be rebounded. If we say 44%
of missed free thows can be rebounded and assume 30% for the offense we come up
with .133 points gained per missed free thows. In Iverson's case 11.16 -
9.03 gives 2.13 missed free throws. Multiply by .133 gives .28 additional
points gained for a total gain of 5.40 points for the Nuggets on free throws for
Iverson. final value = ftm + ftx*.133 - fta*.44. I still like to use .15 and .5
for quicker calculations and very little change.
Rebounds
Standard fare for most linear weights. I used to use 1/3 and 2/3 way back when
offensive rebounds occured on about 1/3 of missed shots. I'll give myself credit
in saying I was using these weights before I noticed the same weights being used
elsewhere. First time I saw this was in PER but I don't know if it had been done
elsewhere. Anyway. We said a missed shot is worth .3 points because of the
possibility of offensive rebounds on 30% of misses. The average offfensive
rebound yields an average of 1 point on the current trip for the offense. We
already credited .3 to the shooter so we credit the remaining .7 to the
offensive rebounder. If the missed shot is rebounded by the defense than the
trip will yield 0 points negating the .3 for the shooter for a difference of .3
gained by the defensive rebounder.
Assists
It's pretty much agreed that weighting assists is very much subjective. I use .8
for assists. If we were to assign full credits to unassisted baskets and split
credit between passer and shooter on assisted passes the ratio of assist
credits to field goal credits plus assist credits would be a little over
two-thirds at just under 70%. An average NBA games nets about 23 assists per
team. In our system made field goals in a game would net 31.6 credits on twos
and 10.2 on threes (6.8 threes on average per game) for a total of 41.8. If we
multiply 23 assists times .8 we get 18.4 credits for assists in a game. The
ratio is still just under 70 percent. ( 41.8 / (41.8 + 18.4) )
Later on we will multiply our weights by .7 in order to share shot credits
properly. If we call made shots .7 (1 * .7) and made threes 1.05 (1.5 * .7) and
assists .56 ( .8 * .7) over the course of a game we end up with approximately 1 credit assigned per shot made.
The other reason I like .8 is that it equates well with rebounding. I don't
think we can easily say that passing is more or less important than rebounding.
When we use .8 as the assist weight we get about 18 credits for an average game
in assists and rebounds. As a bonus I can avoid adjusting by position because it
keeps the TRU score comparable across positions.
Steals and Turnovers
Pretty straight forward. A turnover turns your typical 1 point possession to 0
points. Turnovers then cost a point. Steals gain a point. Arguments can me made
that we are double counting. We kinda are. However when it comes to categories
that are not directly related to scoring we're more concerned with how it
compares to other stats. We know we lose on average one point per turnover.
Blocks
Blocks we set at .8. Most blocks occur on two point attempts. Successful blocked
shots mean rebound chances for the blocking team. Unsuccessful block attempts
mean more made shots (53% on twos if we assume no blocks for a team all game
long) or more fouls. I calculated 1.12 less points per shot attempt if we
include shots that could have turned into free throw attempts. With the
defensive team still acquiring the ball 70% of the time we get .784. We round
that to .8
Fouls
For fouls we are also using .35. I used to not weigh these at all but have since
added it. About 12 possessions per game end as a result of a foul. We are
looking at around 20 free throws made. 6 misses and about 20 fouls per game. The
20 free throws on 12 possessions gives +8 points. About six missed free
throws add .8 points (.133*6) 8.8 points on 20 fouls results in .44 points per
foul. We need to adjust for the fact that about 12 percent of personal fouls (ie
charging) are turnovers now we are down to .387 per foul. We can fudge this down
to .35 using the common logic that many fouls are good fouls.
Putting it all together
Part IV we will summarize this all into one formula and we will take a look at
our adjustments. These adjustments to TRU will show how many actual points a
player adds to the team. We then use these points to show wins produced and net
wins.
